Author Topic: CAN shield pin tied to ground?  (Read 3259 times)

Offline spittet

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CAN shield pin tied to ground?
« on: April 24, 2017, 03:30:56 PM »
Hi,

In the MC controllers and in the Input/Output modules, does the CAN shield (pin#5) is tied to ground internally?

Is it connected to anything?

I'm asking because I want to improve my wiring by using the best grounding of the shield for the CAN network and as I understand it, the shield must be grounded only at one place and I want to know if it's grounded at the controllers.

Sam

Offline FStelzer

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Re: CAN shield pin tied to ground?
« Reply #1 on: April 24, 2017, 03:46:44 PM »
Hello,

as far as I know, there is no intern connection to ground.

Regards,
Florian

Offline FluidPowerTom

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Re: CAN shield pin tied to ground?
« Reply #2 on: April 24, 2017, 05:11:55 PM »
It is connected to ground through a resistor and capacitor.  I had an issue recently where I asked about the exact details on this.  The resistor-capacitor to ground, as I understand, is better for filtering out oscillating EMI.  Because it's tied to ground through a resistor and capacitor it's okay (better in fact) to connect  the CAN shield pin on multiple devices.  As far as also tying directly to ground that's in the J1939 spec, but generally I think it should be fine by just using one or more shield puins.
Mechanical Engineer
Hydra-Power Systems - Distributor - Pacific Northwest

Offline spittet

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Re: CAN shield pin tied to ground?
« Reply #3 on: April 24, 2017, 06:40:43 PM »
Ok, so I'll connect all the CAN shield pins to the shield of the cable and I will not connect the shield of the cable to an external grounding point.

It's not that I have any EMI problems, but I like to do things the good way when it's possible  :).

Thank you!

Sam